1. Field of the Invention
The invention relates to the construction industry and, in particular, concerns a method of interconnecting building members to anchor structures.
2. Description of the Related Art
In typical residential and light industrial/commercial building frame wall construction, load bearing frame walls are comprised of a series of studs and posts that are anchored to the foundation and covered with sheathing material installed over both sides of the frame. Typically, the frame is constructed from a number of vertically extending studs that are positioned between and interconnected with upper and lower plates. The lower plates and/or vertical studs are typically anchored to the foundation in some fashion. The covering material, plywood, sheet rock, siding, plaster, etc. is then attached over the studs.
Natural forces commonly occur that impose vertical and horizontal forces on the structural elements of the buildings. These forces can occur during earth movement in an earthquake and from high wind conditions such as hurricanes, tornadoes, cyclones, or other extreme weather conditions. If these forces exceed the structural capacity of the building, they can cause failures leading to damage to or the collapse of the building with resultant economic loss and potential injuries and loss of life.
A typical method of securing a frame to a foundation is to connect one end of a length of metal strapping to an end of wall stud and to embed the other end in the concrete foundation. Uplift forces acting on the building frame are resisted through the embedded strap. The use of metal strapping is convenient to install, but has strength limitations to inhibit uplift. In particular, the metal strapping is typically attached to a frame member such as a post using relatively few fasteners. Thus, each of the fasteners are subjected to a relatively large fraction of the transferring force, increasing the likelihood of the fastener or its attachment points failing.
Another need in existing construction materials and techniques arises with respect to the vertical loads carried by a building""s frame. The gravity weight of a building and its contents direct a vertical load that is typically transferred to and carried by the vertical load bearing studs or posts of the building""s frame. These vertical members typically bear at their lower end on a pressure treated mudsill.
A mudsill typically comprises a number of 2xc3x974 pieces of lumber placed directly on a foundation so as to lay on the face defined by the 4xe2x80x3 dimension and the longest dimension. A mudsill is also used as a nailing surface along the lower extent of the exterior walls. The inherent structural problem with the mudsill, comprising a wooden member, is that it has less capacity to resist crushing because of the orientation of the grain of the wood. A compressive distortion in the mudsill allows the vertical load-bearing studs to move downwards due to the incident vertical load. Compressive movement of the vertical end studs in a shear panel creates deflection in the walls of the building, weakening the overall structure, providing impetus for cracks to form in the external and interior wall finishings, and potentially concentrating load stresses in unforeseen and damaging ways.
Furthermore, devices that fasten vertical members such as posts to the foundation do so in a substantially rigid manner. In certain force situations, having a substantially rigid and strong interconnection of the post to the foundation may lead to failures at another location.
From the foregoing, it can be appreciated that there is a continuing need for a method and device to continuously secure and anchor a building frame to a foundation. The desired anchoring method should be convenient to install, yet offer strength advantages to the existing use of metal strapping. It would be an additional advantage for the device to be capable of supporting vertical compression loads as well as tension loads to thereby enable the device to transfer loads directly to the foundation. There is a need for a attachment apparatus that permits use of ductile elements so as to allow the attachment apparatus to dissipate a portion of the tension or compression loads, while transferring the rest to the foundation.
The aforementioned needs are satisfied by the device for transferring tension and compression forces incident on a vertical support of a building of the present invention. In one aspect, the device comprises an attachment member having at least one planar surface that is sized to be attached to the vertical support of the building, the attachment member includes a laterally extending section that extends outward from the planar surface. The device further comprises, in this aspect, a load piece that is attached to the attachment member. The load piece includes a mounting section that defines a recess and the load piece receives the laterally extending section in the mounting section such that the laterally extending section reinforces the mounting section. In this aspect, the load piece has upper and lower surfaces that define opening through which the anchor bolt can be extended and coupled thereby securing device to the foundation. The use of two separate pieces, one of which is attached to the building support and the other being attached to the foundation results in a more rigid structure better able to transfer forces without deformation.
In one implementation, the device includes a laterally extending piece that extends underneath the vertically extending member such that the vertically extending member is spaced from the foundation. This permits the use of non-pressure treated wood to be used in the vertical extending member thereby permitting costs savings in construction.
In another implementation, the device includes a spring member that is attached to the anchor bolt such that uplift forces that are transferred from the vertical building support are at least partially absorbed by the spring structure. In one embodiment, the spring structure is mounted so as to be mechanically coupled to the mounting section of the mounting member such that uplift forces result in compression of the spring.
In another aspect of the invention, the invention comprises a device for transferring tension and compression forces incident on a vertical support of a building to an anchor bolt extending out of the foundation of the building. The device comprises an attachment member having a planar surface that is attachable to the vertical support of the building wherein the attachment member is shaped so as to define a reinforcing section that extends outward from the planar surface. The device further comprises a mounting member that is attached to the attachment member, wherein the mounting member includes a planar surface that is shaped so as to define a mounting section that defines a recess which receives the reinforcing section of the attachment member. The mounting member further includes openings so as to permit the anchor bolt to extend therethrough such that when the anchor bolt is mechanically coupled to the mounting section and the planar surface of the attachment member is attached to the vertical support tension and compression forces incident on the vertical support of the building can be transmitted to the anchor bolt.
In this aspect, the attachment member and the mounting member are formed of shaped pieces of metal wherein a generally planar piece of metal is bent and cut to form the desired shapes. In this way, significant manufacturing costs savings can be achieved.
Hence, the device of the present invention provides a more effective, low cost hold down structure. These and other objects and advantages will be more apparent from the following description taken in conjunction with the accompanying drawings.